1. Field of the Invention
The invention pertains to a vibration damper, comprising a damping element and a pneumatic spring, wherein the damping element has a container tube, which is connected to a roll-off piston of the pneumatic spring. The roll-off piston is connected by an air suspension bellows acting as a rolling diaphragm to an external guide, mounted concentrically and with freedom of axial movement with respect to the roll-off piston. The air suspension bellows and the roll-off piston form the boundaries of a space filled with pressurized gas.
2. Description of the Related Art
Vibration dampers of the type described above are used in motor vehicles, in which they form part of the suspension which supports, for example, the driver's cab of a commercial vehicle on the chassis to isolate the driver's cab as effectively as possible from the vibrations introduced from the roadway into the chassis via the wheel suspensions. The external guide of the pneumatic spring and the piston rod of the damping element are connected to the cab, whereas the damping element is connected by way of an attachment part to the chassis; the operation of the pneumatic spring depends on its geometric dimensions, on the pressure prevailing in the gas space, and on the profile of the roll-off piston, over which the air suspension bellows rolls. The solution to the problem of sealing off the gas space from the atmosphere all the way around the container tube, this gas space also extending to the space around the piston rod, namely, by the use of an O-ring between the roll-off piston of the pneumatic spring and the container tube of the damping element, belongs to the state of the art. To divert the axial force component created by the high pressure in the gas space into the container tube, the conventional design provides an adapter ring, which requires a great deal of effort to manufacture and which must be welded to the container tube. In addition, the O-ring is installed in or near the adapter ring, which complicates the design and makes it more expensive. A contour of the roll-over piston is supported axially against the adapter ring, which absorbs the axially oriented forces of the pneumatic spring and diverts them into the container tube. The larger the number of units produced, however, the greater the need for rationalizing the means used to provide the above-mentioned support and sealing of the roll-over piston on the container tube.